Well injection and production method and system

ABSTRACT

A method and system for enhancing petroleum production are provided, in which petroleum is displaced from a fractured formation by selectively injecting fluid into selected fractures in the formation without injecting into the other non-selected fractures. The injected fluid flows out into the fractured formation and enhances recovery from the non-selected fractures. Petroleum is selectively collected from the non-selected fractures.

PRIORITY APPLICATION

This application claims priority to U.S. provisional application Ser.No. 61/763,743, filed Feb. 12, 2013.

FIELD

The invention relates to a method and a system for petroleum production,and more specifically to a method and a system for enhancing petroleumproduction in a well.

BACKGROUND

Petroleum recovery from subterranean formations (sometimes also referredto as “reservoirs”) typically commences with primary production (i.e.use of initial reservoir energy to recover petroleum). Since reservoirpressure depletes through primary production, primary production issometimes followed by the injection of fluids, including for examplewater, hydrocarbons, chemicals, etc., into a wellbore in communicationwith the reservoir to maintain the reservoir pressure and to displace(sometimes also referred to as “sweep”) petroleum out of the reservoir.One issue with injecting fluids to enhance petroleum recovery is how toefficiently sweep the reservoir fluids and expedite production.

In general, petroleum produces from a well due to the presence of adifferential pressure gradient between the far field reservoir pressureand the pressure inside the wellbore. As the well produces, thereservoir pressure gradually decreases and the pressure gradientdiminishes over time. This reduction in reservoir pressure usuallycauses a decline in production rates from the well.

Further, the permeability of the desired production fluid (i.e. liquidpetroleum) within the reservoir rock reduces in the presence of anotherphase (e.g. gas phase). The presence of another phase has the effect ofreducing the flow rate of the desired production fluid from thereservoir to the wellbore. In general, the reservoir fluid comprises amixture of several types of hydrocarbons and other constituents. Thephase of many of the constituents is dependent on the pressure andtemperature of the reservoir. As the pressure of the reservoir reducesthrough production, some of the dissolved constituents may come out ofsolution and become a free gas phase. These gas-phase constituents maycollect near the well in any region of the reservoir where the pressurehas reduced to below the bubble point, which may block liquid petroleumfrom producing into the wellbore. This problem of two-phase flowresulting from reservoir pressure depletion may be prevented orminimized by injecting fluid into the wellbore to maintain reservoirpressure.

The oil and gas industry has progressed from producing petroleum usingvertical wells to horizontal wells which are hydraulically stimulatedcreating transverse fractures that are typically perpendicular butsometimes are at oblique angles to the horizontal wellbore. Thesemulti-fractured horizontal wells (MFHW) are typically used in tight orshale gas and/or oil formations to improve well productivity. However,the decline rates of these MFHW may be very severe, which provides anopportunity for using a method for enhancing petroleum recovery.

SUMMARY OF THE INVENTION

According to a broad aspect of the invention, there is provided a methodfor petroleum production from a well having a well section with awellbore inner surface in communication with a plurality of fractures ina formation containing reservoir fluid, the method comprising: creatinga first set and a second set of zones in the well section, each zone forcommunicating with at least one of the plurality of fractures, and thefirst set of zones being fluidly sealed from the second set of zones inthe well section; and selectively injecting injection fluid into theformation via at least one zone in the first set of zones.

According to another broad aspect of the invention, there is provided amethod for hydrocarbon production from a well having a well section witha wellbore inner surface in communication with a first set and a secondset of fractures in a formation containing reservoir fluid, the methodcomprising: creating a plurality of injection zones in the well section,each injection zone for communicating with at least one fracture in thefirst set of fractures at the wellbore inner surface; creating aplurality of production zones in the well section, each production zonefor communicating with at least one fracture in the second set offractures at the wellbore inner surface and for receiving reservoirfluid from the formation via the at least one fracture in the second setof fractures, each production zone being fluidly sealed from theinjection zones inside the well section; selectively injecting injectionfluid into the formation via at least one of the injection zones;selectively collecting reservoir fluid from the formation via at leastone of the production zones; and transporting the collected reservoirfluid to surface.

According to yet another aspect of the present invention, there isprovided a method for petroleum production involving a first well havinga first well section with a first wellbore inner surface incommunication with a first set of fractures in a formation containingreservoir fluid and a second well having a second well section with asecond wellbore inner surface in communication with a second set offractures in the formation, wherein some of the fractures in the firstset are in close proximity to some of the fractures in the second set,the method comprising: creating a plurality of injection zones in thefirst well section, each injection zone for communicating with at leastone of the fractures in the first set that are in close proximity tosome of the fractures in the second set, via the first wellbore innersurface; creating a plurality of production zones in the second wellsection, each production zone for communicating with at least one of thefractures in the second set that are in close proximity to some of thefractures in the first set, via the second wellbore inner surface, theplurality of production zones configured to receive reservoir fluid fromthe formation; selectively injecting injection fluid into the formationvia at least one of the injection zones; selectively collectingreservoir fluid from the formation via at least one of the productionzones; and transporting the collected reservoir fluid to surface.

According to another broad aspect of the invention, there is provided asystem for petroleum production from a well having an inner bore and awell section with a wellbore inner surface in communication with a firstset and a second set of fractures in a formation containing reservoirfluid, the system comprising: an injection conduit extending inside theinner bore and along at least part of the well section; a productionconduit extending inside the inner bore and along at least part of thewell section; at least one injection zone in the well section forcommunicating with at least one fracture in the first set of fracturesat the wellbore inner surface; at least one production zone in the wellsection for communicating with at least one fracture in the second setof fractures at the wellbore inner surface, the at least one productionzone being fluidly sealed from the at least one injection zone insidethe well section; at least one injection flow regulator in associationwith the at least one injection zone, the at least one injection flowregulator having an open position which allows fluid communicationbetween the injection conduit and the at least one fracture in the firstset of fractures via the at least one injection zone, and a closedposition which blocks fluid communication between the injection conduitand the at least one fracture in the first set of fractures; and atleast one production flow regulator in association with the at least oneproduction zone, the at least one production flow regulator having anopen position which allows fluid communication between the productionconduit and the at least one fracture in the second set of fractures viathe at least one production zone, and a closed position which blocksfluid communication between the injection conduit and the at least onefracture in the second set of fractures.

According to yet another broad aspect of the invention, there isprovided a method for producing petroleum from a well having a wellborewith a wellbore inner surface, the wellbore communicable via thewellbore inner surface with a first set and a second set of fractures ina formation containing reservoir fluid, the method comprising: supplyinginjection fluid to the wellbore via a conduit; injecting injection fluidfrom the wellbore to the formation through the first set of fractures,while blocking fluid flow to and from the second set of fractures;ceasing the supply of injection fluid; blocking fluid flow to and fromthe first set of fractures; permitting flow of reservoir fluid from theformation through the second set of fractures into the wellbore; andcollecting reservoir fluid from the wellbore via the conduit.

According to another broad aspect of the invention, there is provided asystem for petroleum production from a well having a well section with awellbore inner surface and an iimer bore, the inner bore beingcommunicable with fractures in a formation via the wellbore innersurface, the system comprising: a conduit extending down the well, theconduit having a lower end in or near the well section and being influid communication with the inner bore of the well section; and aplurality of flow regulators at or near the wellbore inner surface, eachbeing connected to at least one of the fractures and being selectivelyopenable and closeable for allowing and blocking, respectively, fluidcommunication between the inner bore and the at least one of thefractures.

According to another broad aspect of the invention, there is provided amethod for petroleum production from a well having a well section with awellbore inner surface in communication with a plurality of fractures ina formation containing reservoir fluid, the method comprising: creatinga plurality of zones in the well section, each zone for communicatingwith at least one of the plurality of fractures and each zone beingfluidly sealed from adjacent zones in the well section, and two or morezones are fluidly connectable via a conduit extending through theplurality of zones; selectively supplying injection fluid from theconduit to at least one of the zones and injecting the injection fluidinto the formation via the at least one of the zones; selectivelycollecting reservoir fluid into the conduit from the formation via atleast one of the zones, and the injection of injection fluid and thecollection of reservoir fluid occurring asynchronously; transporting thecollected reservoir fluid to surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Drawings are included for the purpose of illustrating certain aspects ofthe invention. Such drawings and the description thereof are intended tofacilitate understanding and should not be considered limiting of theinvention. Drawings are included, in which:

FIG. 1 is a schematic diagram illustrating one embodiment of theinvention;

FIG. 2 is a cross-sectional view of one embodiment of the invention,where the system is installed in a cased and cemented horizontal wellsection;

FIG. 3 is a cross-sectional view of another embodiment of the invention,where the system is installed in an unlined openhole horizontal wellsection;

FIG. 4 is a cross-sectional view of yet another embodiment of theinvention, where one conduit is inside the other conduit;

FIG. 5 is a cross-sectional view of another embodiment of the invention,where one conduit is inside the other conduit;

FIG. 6 is a cross-sectional view of still another embodiment of theinvention, where one conduit is inside the other conduit;

FIG. 7 is a schematic diagram illustrating another embodiment of theinvention, which involves two adjacent wellbores;

FIG. 8 is a cross-sectional view of another embodiment of the invention,where one conduit is used for both injection and production;

FIG. 9 is a cross-sectional view of yet another embodiment of theinvention, where one conduit is used for both injection and production;

FIGS. 10 a and 10 b are a perspective view and a cross-section view,respectively, showing an embodiment of a bypass tube usable with thepresent invention; and

FIGS. 11 a and 11 b are a perspective view and a cross-section view,respectively, showing another embodiment of a bypass tube usable withthe present invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various embodiments of thepresent invention and is not intended to represent the only embodimentscontemplated by the inventor. The detailed description includes specificdetails for the purpose of providing a comprehensive understanding ofthe present invention. However, it will be apparent to those skilled inthe art that the present invention may be practiced without thesespecific details.

An aspect of the present invention is to provide a scheme and a systemfor use with a horizontal wellbore to allow simultaneous injection offluid(s) for pressure maintenance and effective sweeping and productionof petroleum out of the formation.

In one aspect, a method is described herein for enhancing petroleumproduction from a well having alternating injection and productionpattern through the induced transverse fracture network so the injectedfluid(s) may effectively sweep hydrocarbons linearly from one stage ofinduced fracture(s) (e.g. an injection stage) into an adjacent stage ofinduced fracture(s) (e.g. a production stage). This pattern can berepeated as many times as required depending on the number of fracturestages in the wellbore. This well injection and production method may beused for each well in a reservoir having multiple horizontalspaced-apart wells so that the effects of this method may be multiplied.The spacing between the injection and production interval can beadjusted to account for the formation permeability (i.e. tighter spacingfor lower permeability formation).

In one broad aspect of the present invention, petroleum is displacedfrom a fractured wellbore by creating a plurality of zones, each inconununication with at least a fracture in the wellbore, and selectivelyinjecting a fluid into selected zones without injecting into the othernon-selected zones. The selected zones and non-selected zones arefluidly sealed from one another in the wellbore. The injection fluidflows out into the fractured formation and enhances recovery in thenon-selected zones. The non-selected zones are selectively allowed ornot allowed to produce, depending on the circumstances. A sample methodand system of the invention are disclosed herein.

Referring to FIGS. 1 to 6, a well has a heel transitioning from asubstantially vertical section to a substantially horizontal section.The well may or may not be cased. The substantially horizontal sectionof the well is in communication with a plurality of fractures F in aformation 8 adjacent to the well, via a wellbore inner surface 11, atvarious locations along the length of the horizontal section.

In the illustrated embodiment in FIG. 2, at least a portion of thehorizontal section of the well is lined with a casing string 14. Thecasing string 14 may be cemented to a wellbore wall 10 by a layer ofconcrete 15 formed in the annulus between the wellbore wall 10 andcasing string 14. The casing string and concrete has intermittentperforations 13 along a lengthwise portion of the horizontal sectionwhich provide passage ways connecting the inner surface of the casingstring and fractures F. For a cased well, the wellbore inner surface 11of the horizontal section is the inner surface of the casing string 14.In one embodiment, a system of openhole packers (not shown) is providedon the outer surface of the casing string with valves placedtherebetween, whereby the annular space between adjacent openholepackers can be hydraulically accessed via the valves.

In an embodiment as illustrated in FIG. 3, the well is uncased so thewellbore is in direct communication with the fractures F via wellborewall 10. For an uncased well, the wellbore inner surface 11 of thehorizontal section is the wellbore wall 10. A person of ordinary skillin the art would know whether it would be beneficial to case thewellbore and/or to cement the casing 14 to the formation.

Fractures F may be natural fractures occurring in the formation,fractures that are formed by hydraulic fracturing, or a combinationthereof. While fractures F are shown in the Figures to extendsubstantially perpendicular to the lengthwise axis of the horizontalsection, fractures F may extend away from the wellbore at any anglerelative to the lengthwise axis.

There are a number of ways to initiate hydraulic fractures at specificlocations in the wellbore, including for example by hydra jet, by stagedhydraulic fracturing using various mechanical diversion tools andmethods applicable to open wells or cased wells, by using a limitedentry perforation and hydraulic fracture technique (which is generallyapplicable to cased cemented wells), etc. Other techniques for placingmultiple hydraulic fractures in a horizontal well section include forexample: a multiple repeated sequence of jet perforating the casedcemented hole followed by hydraulic fracturing with temporary isolationinside the wellbore using mechanical bridge plugs; wireline jetperforating the cased and cemented hole to initiate the hydraulicfracture at a specific interval while preventing the fracture treatmentfrom re-entering previously fractured intervals using perforation ballsealers and/or other methods of diversion; hydra jet perforating witheither mechanical packer or sand plug diversion; various open-holepacker and valve systems; and manipulating valves installed with thecemented casing using coiled tubing or jointed tubing deployed tools.

With reference to FIGS. 1 to 4, a system is shown for facilitatingpetroleum production from the formation 8. The system comprises aninjection conduit 18 and a production conduit 20, both of which extendinto the horizontal section of the wellbore. The injection conduit 18supports injection flow regulators 22 at intermittent locations along alengthwise section thereof to allow fluids inside the conduit to flowout via the flow regulators 22. The production conduit 20 supportsproduction flow regulators 24 at intermittent locations along alengthwise section thereof to allow fluids from outside the conduit toflow into the conduit via the flow regulators 24. One or both ofconduits 18 and 20 may also include packers 16 that are positionedintermittently along a lengthwise portion thereof. Regulators 22 and 24and packers 16 will be described in more detail hereinbelow.

Injection conduit 18 and production conduit 20 are separate flowchannels such that the flow of fluids in one conduit is independent ofthe other. In one embodiment, as illustrated in FIGS. 1, 2 and 3,injection conduit 18 is positioned side-by-side with and substantiallyparallel to production conduit 20. In an alternative embodiment, one ofthe conduits may be inside the other. For example, as shown in FIGS. 4to 6, the production conduit 20 is placed inside injection conduit 18,and is optionally substantially concentric with injection conduit 18.Further, the position of one conduit relative to the other may varyalong the length of the well. For example, as shown in FIG. 5, theproduction conduit 20′ is inside injection conduit 18′ above thehorizontal section of the well, and the injection conduit 18″ becomesthe inside conduit along the horizontal section through the use ofbypass tubes at or near the heel of the well. However the conduits arepositioned relative to one another, the operation of each of theconduits is independent from one another so the flow of fluids in eachconduit can be separately controlled.

In whichever configuration, the diameters of the conduits are sized suchthat: (i) the conduits can be easily run into the wellbore; (ii) theconduits allow for the flow of either production or injection fluids atsuitable flow rates; and (iii) when the conduits are in a desiredposition downhole, there is at least some space between the wellboreinner surface 11 and the outer surface of at least one of the conduits.

In one embodiment, the production conduit comprises jointed tubing, thelength and quantity of which may depend on the measured depth of thewell and/or the length of the fractured portion of the well. In afurther embodiment, the production conduit is closed at one end (i.e.the lower end) and may have a substantially uniform diameter throughoutits length. In another embodiment, the production conduit has agraduated diameter along its length, with the larger diameter portionabove the uppermost packer or above a pump, if one is included fortransporting the petroleum from the production conduit.

Tubing that meets American Petroleum Institute (API) standards andspecifications (“API tubing”) may be used for the production conduitand/or the injection conduit. Proprietary connection tubing and/ortubing that has a smaller outside diameter at the connections thanspecified by API may also be used. Alternatively, non-API tube sizes maybe used for all or a portion of the production conduit and/or theinjection conduit.

In a sample embodiment, the production conduit tubing for installationin the fractured section of the well has an outer diameter rangingbetween about 52.4 mm and about 114.3 mm, preferably with API orproprietary connections and a joint length of approximately 9.6 in, fora well wherein at least a portion of the fractured section is cased, andwherein the casing string has an outer diameter ranging between about114.3 and about 193.6 mm. In another sample embodiment, a productionconduit tubing having the above-mentioned characteristics may also beused in an uncased well, wherein the open-hole diameter in the fracturedsection ranges between about 155.6 and about 244.5 mm.

In one embodiment, the injection conduit comprises coiled tubing, APIjointed tubing, or proprietary tubing. The length and quantity of theinjection conduit tubing may depend on the measured depth of the welland/or the length of the fractured portion of the well. In a furtherembodiment, the injection conduit is closed at one end (i.e. the lowerend) and may have a substantially uniform diameter throughout itslength. If coiled tubing is used for the injection conduit, the outerdiameter of the injection conduit tubing may range from about 19 mm toabout 50.8 mm. In a preferred embodiment, the coiled tubing for theinjection conduit has an outer diameter of approximately 25.4 mm. Ifjointed tubing is used for the injection conduit, the outer diameter ofthe injection conduit tubing may range from about 26.67 mm to about101.6 mm. In another sample embodiment, a production conduit tubinghaving the above-mentioned characteristics may also be used in anuncased well, wherein the open-hole diameter in the fractured sectionranges between about 155.6 and about 244.5 mm.

In a side-by-side configuration as illustrated in FIGS. 1 to 3, thejointed tubing for the injection conduit, for example, has an outerdiameter of approximately 26.67 mm, and the production conduit tubinghas an outer diameter of approximately 60.3 mm. In a systemconfiguration wherein one conduit is disposed inside the other, asillustrated in FIGS. 4 to 5, the outer conduit for example has an outerdiameter of approximately 101.6 mm and the inner conduit has an outerdiameter of approximately 52.4 mm. In another sample systemconfiguration wherein one conduit is placed inside the other asillustrated in FIG. 6, the outer conduit's outside diameter isapproximately 114.3 mm and the inner conduit's outer diameter isapproximately 60.3 mm.

In one embodiment, both the injection and production conduits along withany downhole sensors, instruments, electric conductor lines andhydraulic control lines are housed inside a single encapsulated cable.The type of encapsulated cable produced by Teclmip Umbilical Systems maybe used but modifications may be required to accommodate packers andvalves thereon.

The production conduit is for transporting fluids from the wellbore tothe surface of the wellbore opening. The fluids received by theproduction conduit are referred to as “produced fluids”. The injectionconduit is for transporting injection fluid from at least the wellboreopening into the wellbore.

Injection fluid (sometimes also referred to as “injectant”) includes forexample water, gas (e.g. nitrogen, and carbon dioxide), and/or petroleumsolvent (e.g. methane, ethane, propane, carbon dioxide, or a mixturethereof), with or without chemical additives. However, any fluid thatcan become miscible to the petroleum in-situ may be used as theinjectant since miscible floods have shown to produce superiorhydrocarbon recovery factors over immiscible floods.

The injection fluid may be supplied to the injection conduit from asupply source at surface. Alternatively or additionally, injection fluidmay be recovered and separated from the produced fluids, and thencompressed and re-injected into the injection conduit. In oneembodiment, any or all of the recovering, separating, compressing, andre-injecting of injection fluid may be performed downhole.

In one embodiment, the composition of the injection fluid may beselected based on its solubility in the reservoir petroleum. The processof using a dissolvable injection fluid to sweep reservoir petroleum issometimes referred to as “hydrocarbon miscible solvent flood,” or HCMF.Examples of hydrocarbon miscible solvents include for example methane,ethane, propane and carbon dioxide. The dissolution of certain solubleinjection fluids into the reservoir petroleum generally lowers theviscosity of the latter and reduces interfacial tension, therebyincreasing the mobility of the petroleum within the reservoir. Thisprocess may improve the rate of production and increase the recoveryfactor of petroleum recoverable from the reservoir.

Packers are usually used to divide a wellbore into sections and areusually placed downhole with or as a component of a downhole tool.Packers 16 may include various types of mechanisms, such as swellablerubber packer elements, mechanical set packer elements and slips, cups,hydraulic set mechanical packer elements and slips, inflatable packerelements, seal bore, seal combination, or a combination thereof.

Packers are generally transformable from a retracted position (sometimesalso referred to as a “running position”) to an expanded position(sometimes also referred to as a “set position”). The packers are in theretracted position when the downhole tool is run into the wellbore, suchthat the packers do not engage the inner surface of the wellbore tocause interference during the running in. Once the downhole tool ispositioned at a desired location in the wellbore, the packers areconverted to the expanded position. In the expanded position, thepackers engage the wellbore wall if the well is uncased or the casingstring if the well is cased (collectively referred to herein as the“wellbore inner surface”) and may function to fluidly seal the annulusbetween the downhole tool and the wellbore inner surface, and may alsofunction to anchor the downhole tool (or a tubing string connectedthereto) to the wellbore inner surface.

In one embodiment, as shown for example in FIGS. 1 to 3, packers 16 areconnected to both conduits. In the sample embodiments shown in FIGS. 4to 6, packers 16 are connected to one of the conduits. Packers 16 may beconnected to one or both of the conduits in various ways, including forexample, by threaded connection, friction fitting, bonding, welding,adhesives, etc. In one embodiment, packers 16 are configured to beexpandable from the outer surface of at least one of the conduits. Thepackers are spaced apart along the length of the conduits such thatadjacent flow regulators 22 and 24 are separated by at least one packer.Alternatively or additionally, adjacent packers may have one or moreinjection flow regulators 22 or production flow regulators 24 positionedtherebetween.

In a preferred embodiment, packers 16 are mechanical feedthrough-typepackers having a hydraulic-setting mechanism. Generally,feedthrough-type packers allow the passage of conduit(s), electricalconductor line(s), and/or communication line(s) therethrough. In afurther preferred embodiment, packers 16 are feedthrough-type swellablepackers (sometimes also referred to as cable swellable packers) thatallow at least one of the conduits to connect thereto and extendtherethrough. In one embodiment, the packers are attached in theretracted position to the production conduit pre-run in and are expandedafter the conduits are at a desired location downhole. In the expandedposition, the packers engage the wellbore and fill a portion of theannulus between the inner surface of the wellbore and the outer surfacesof the conduits. In one embodiment, packers 16 are configured to expandradially outwardly from the outer surfaces of the conduits. Onceexpanded, each packer creates a seal with the wellbore inner surfacesuch that fluid can only flow from one side of the packer to the otherside through the conduits.

In a sample embodiment, one or more of the packers may be manufacturedon or connected to a section of tubing, which may range from about 3 mto about 9.6 m in length, and the tubing having a packer thereon isconnected at both ends to production conduit tubings. In a furtherembodiment, the packer has a length ranging from about 1 m to about 5 m.The connection between the packer tubing and the production conduittubing may be an API specification or proprietary design threadedconnection. In a sample embodiment, packers 16 are made of anelastomeric polymer bladder that is inflatable upon injection of a fluidtherein. The types of fluid that may be used to inflate the packersinclude for example oil and water.

Preferably, packers 16 are positioned in between fractures orperforations 13 (if the well is cased). The locations of the fracturesmay be determined by the location of the perforations in the casingaccording to the executed completion plan, or by microseismic monitoringor logging. Logging methods may include radioactive tracer, temperaturesurvey, fiber optic distributed temperature sensor survey, or productionlogging. Generally, adjacent hydraulic fractures are spaced apart byapproximately 100 m, but sometimes the distance between adjacenthydraulic fractures in a horizontal well may range from about 20 toabout 200 m. In one embodiment, packers 16 are positioned in thewellbore such that there are one or more fractures between adjacentpackers. It is not necessary that the packers 16 are evenly spaced alongthe horizontal section of the well. The distance between adjacentpackers may vary.

Preferably, each packer 16 creates a seal with the wellbore innersurface 11 such that fluid can only flow from one side of the packer tothe other side through one of the conduits. The space defined by thewellbore inner surface 11 and the outer surface of one or both of theconduits, in between two adjacent packers, and in communication with atleast one fracture, is referred to hereinafter as a “zone.” Adjacentzones are fluidly sealed from one another. Preferably, each zone permitsthe flow of fluids thereto from one or more fractures F and/or from theinjection conduit 18.

Referring to FIGS. 2 to 5, flow regulators 22 of the injection conduitallow selective introduction of injection fluid from the conduit intothe wellbore. More specifically, flow regulators 22 help distribute andcontrol the flow of injection fluid into selected zones. Preferably, theflow regulator 22 has at least an open position and a closed position.In the open position, the regulator 22 allows fluid flow therethrough.In the closed position, the regulator 22 blocks fluid flow. The openposition may include one or more partially open positions, includingchoked, screened, etc., such that the rate of fluid flow therethroughmay be selectively controlled.

A number of devices may be used for flow regulators 22, including forexample sliding sleeves, tubing valves, chokes, remotely operatedvalves, and interval control valves. Remotely operated valves are valvesthat can be hydraulically, electrically, or otherwise controlled from adownhole location and/or the surface of the well opening. However, otherdevices that function in a similar manner as the aforementioned examplesmay also be used. In one embodiment, flow regulators 22 are controllablewith radio-frequency identification (RFID).

In a sample embodiment, the injection flow regulators 22 are chokes,each with a throat diameter configured to generate sufficient pressureresistance to limit the rate at which injection fluid is supplied to theinjection zone downstream of the flow regulator, thereby distributingthe injection fluid in a controlled manner. The chokes may beincorporated into valves to allow “choking” to help control thedistribution of the injection fluid when the valves are in an openposition. In a preferred embodiment, the injection flow regulator 22also comprises a mechanism (for example, a sliding sleeve) that can beselectively closed to prevent substantially all fluid from flowingtherethrough.

In the sample embodiments shown in FIGS. 2 to 5, there is an injectionflow regulator in every other zone, thereby allowing fluid communicationbetween these zones and the injection conduit through the injection flowregulator. A zone that can receive injection fluids from the injectionconduit (for example, through an injection flow regulator) is referredto as an “injection zone”.

Referring to FIGS. 2 to 5, flow regulators 24 of the production conduitallow selective intake of petroleum and/or other fluids from theformation to the production conduit. Preferably, flow regulators 24control when fluids can flow into and/or the types of fluids that canflow into the production conduit. In one embodiment, the flow regulator24 has at least an open position and a closed position. In the openposition, the regulator 24 allows fluid flow therethrough. In the closedposition, the regulator 24 blocks fluid flow. The open position mayinclude one or more partially open positions, including choked,screened, etc., such that the rate of fluid flow therethrough may beselectively controlled.

Additionally or alternatively, the flow regulators 24 may be configuredto have a customized fluid flow path that selectively allows the passageof fluids based on viscosity, density, fluid phase, or a combination ofthese properties. In one embodiment, the flow regulator 24 restricts theflow of fluids having a lower viscosity and/or density than the desiredpetroleum such that fluids with a viscosity and/or density similar tothe desired petroleum flow through the regulator 24 preferentially andinto the production conduit. Flow regulators 24 may therefore restrictundesirable fluids (e.g. water, and gas, such as for example methane,ethane, carbon dioxide, and propane) from flowing into the productionconduit. In a preferred embodiment, flow regulators 24 allow the flow ofliquid petroleum therethrough while limiting the passage of undesiredgas and/or water.

Any device that can selectively allow and/or restrict the flow ofcertain fluids therethrough may be used for flow regulators 24,including for example orifice style chokes, tubes; sliding sleevevalves, remotely operated valves, and autonomously functioning flowcontrol devices. Other devices that function in a similar manner as theaforementioned examples may also be used. In one embodiment, flowregulators 24 are controllable with radio-frequency identification(RFID).

In a sample embodiment, the production flow regulators 24 areautonomously functioning flow regulators, which are self-adjustingin-flow control devices, whereby fluid flow is autonomously controlledin response to changes in a fluid flow characteristic, such as densityor viscosity. Autonomously functioning flow regulators are sometimesmore commonly referred to as Autonomous Inflow Control Device (AICD).The AICD has two main functions: one is to identify the fluid based onits viscosity, and the second in to restrict the flow when undesirablefluids are present. Both of these functions are created by speciallydesigned flow channels inside the device.

AICDs generally utilize dynamic fluid technology to differentiatebetween fluids flowing therethrough. For example, an AICD may beconfigured to restrict the production of unwanted water and gas atbreakthrough to minimize water and gas cuts. Generally, AICDs have nomoving parts, do not require downhole orientation and utilize thedynamic properties of the fluid to direct flow. AICDs may work bydirecting fluids through different flow paths within the device. Higherviscosity oil takes a short, direct path through the device with lowerpressure differential. Water and gas spin at high velocities beforeflowing through the device, creating a large pressure differential.

Preferably, the AICD chokes low-viscosity (undesired) fluids, therebysignificantly slowing flow from the zone producing the undesirablefluids. This autonomous function enables the well to continue producingthe desired hydrocarbons for a longer time, which may help maximizetotal production.

In another sample embodiment, the production flow regulators 24 arevalves that can be remotely opened and closed, such as for exampleintelligent well completion valves, which allow the selective ceasing ofpetroleum flow into the production conduit from one or more productionzones. By closing the flow regulators 24 of one or more production zonesfor a certain period of time, the injection fluid is allowed topenetrate deeper into the reservoir which may help increase petroleumproduction. In a further embodiment, selected production flow regulators24 are closed while the remaining regulators are opened to allowproduction of petroleum, and the pattern or sequence of which regulatorsare opened or closed at any given time may be configured as required tooptimize the performance of the system.

In the sample embodiments shown in FIGS. 2 to 5, there is a productionflow regulator 24 in each of the zones adjacent to the injection zones,thereby allowing each adjacent zone to fluidly communicate with theproduction conduit via the production flow regulator. The zones in whichpetroleum and/or other reservoir fluids can be collected therefrom (forexample, by a production conduit via a flow regulator 24) are referredto herein as “production zones”.

In one embodiment, injection flow regulators 22 are connected to theinjection conduit and/or production flow regulators 24 are connected tothe production conduit. This may be achieved in various ways. Forexample, the flow regulators may be manufactured into tools that have asimilar outer diameter as the conduit and are insertable at almost anyposition along the length of the conduit by, for example, cutting thetubing of the conduit at a desired location and inserting and connectingthe flow regulator tool at the cut. The tool may be connected to thetubing by for example mechanical connection, threaded connection,adhesives, bonding, welding, etc. Mechanical connections include forexample the use of external crimps and external compression sleeves.External crimps may be used to create a seal between the flow regulatortool and the conduit tubing by plastically deforming the tubing on tothe tool. External compression sleeves may be used to seal the outersurface of the tubing at and near the cut. In one embodiment, the flowregulators are made of metal, such as steel, that can withstand wellboreconditions. In a further embodiment, where the flow regulators arechokes, the throat is made of an erosion wear resistant material,including for example tungsten carbide or matrix material containingtungsten carbide, ceramic, or an erosion wear resistant carbonnanostructure.

There are many ways to configure the system of the present invention,for example, by varying the placement and/or location of one or more ofthe production conduit, injection conduit, packers, production flowregulators, and injection flow regulators. In a sample embodiment, asillustrated in FIGS. 2 to 5, the injection flow regulators 22 andproduction flow regulators 24 are offset laterally along the length ofthe conduits such that regulators 22 are not aligned with regulators 24,and adjacent injection flow regulators and production flow regulatorsare separated by a packer 16. Of course, other configurations arepossible.

Further, the number of injection zones 26 and production zones 28 in thesystem may be selectively varied and may depend on the characteristicsof the well, including for example the number of fractures in the well.Each zone may be in communication with one or more hydraulic fractures.Alternatively, there may be as many injection and production zones intotal as the number of hydraulic fractures, but not necessarily.Preferably, the lower end of the production conduit is in communicationwith the lowermost (i.e. farthest away from the well opening) productionzone via a production flow regulator 24. Further, the lower end of theinjection conduit is preferably in communication with the lowermostinjection zone via an injection flow regulator 22.

The pattern of alternating injection and production zones may be aregular periodic pattern or an irregular random pattern along the lengthof the horizontal section of the well. Consecutive production zones maybe separated by one or more injection zones, and vice versa. Forexample, in one configuration, a first injection zone is separated froma second injection zone by one production zone, and the second injectionzone is separated from a third injection zone by three production zones,and the third injection zone is separated from a fourth injection zoneby two production zones.

In one embodiment, at least one production zone may also function as aninjection zone, and vice versa. This may be accomplished, for example,by: (i) using flow regulators that can function as both injection flowregulators and production flow regulators; and/or (ii) usingindependently functioning injection flow regulators and production flowregulators within the same zone. In a further embodiment, all zones areconfigured to allow selective injection of fluid into the reservoir.

In another sample embodiment, the production and injection conduits areset up as shown in FIGS. 2 to 5, wherein the zones alternate betweeninjection zones and production zones along the length of the horizontalsection. The flow regulators 22, in the open position, allow injectionfluid to flow from the injection conduit into the injection zones 26 andinto the fractures that are in communication with the injection zones.In the illustrated embodiments, the general flow direction of theinjection fluid is indicated with arrows “I”.

Production flow regulators 24 allow petroleum and/or other fluids inproduction zones 28 to flow into the production conduit, which may thenflow to or be pumped to surface and be collected. In the illustratedembodiments, the general flow direction of the produced fluid is denotedby arrows “P”. Various methods may be employed to transport thepetroleum in the production conduit to surface, including for example byway of an electric submersible pump, reciprocating subsurface pump,progressing cavity pump, gas lift, etc. or a combination thereof.

As discussed above, flow regulators 24 may be configured to restrict theflow of fluids other than reservoir petroleum into the productionconduit. Some injection fluid may flow into production zones in thegaseous phase as the reservoir is being emptied of liquid petroleum, andflow regulators 24 may prevent most or all of such injection fluid fromentering the production conduit. For example, if the flow regulator 24is a choking or autonomous choking valve type flow regulator, the flowregulator may prevent most low viscosity fluid from entering theproduction conduit. However, if the flow regulator 24 is a surface ordownhole actuated valve, such as a sliding sleeve, the flow regulatormay prevent all fluids from entering the production conduit when theflow regulator is in the closed position. In a preferred embodiment, theproduction flow regulator 24 includes a mechanism (for example, asliding sleeve) that can be selectively closed to prevent substantiallyall fluid from flowing therethrough.

There are situations where it may be desirable to include a productionflow regulator 24 that, when closed, can prevent substantially allfluids from entering the production conduit in the production zone. Forinstance, if the well is poorly cemented such that almost all injectionfluid entering a particular injection zone travels directly from theinjection zone to an adjacent production zone rather than to thereservoir (this event is sometimes referred to as “short circuiting” ofinjection fluid), it would be desirable to have a surface or downholeactuated valve type flow regulator in the adjacent production zone toallow that production zone to be substantially completely shut off fromthe production conduit when the flow regulator therein is in the closedposition. Shutting off the affected production zones in this manner mayhelp reduce the effect of short circuiting, thereby encouraging theinjection fluid to flow into the reservoir.

Another situation where it may be desirable to use surface or downholeactuated valve type flow regulators in production zones to allow theselective shutting off of certain production zones is when there ismassive reservoir heterogeneity within a single horizontal well, whichmay be due to permeability variation or to natural fracture or complexhydraulic fracture swarms locally concentrated within only a part of thewellbore affected reservoir. In this situation, temporarily shutting offcertain production zone(s), while continuing to inject fluid intoinjection zone(s), may cause the injected fluid to enter the reservoirmore deeply and saturate the nearby reservoir fluid and/or cause thereservoir pressure to increase locally. Reopening the shut offproduction zone(s) after a period of time may cause anyinjectant-affected reservoir fluid to drain into production zones, whichmay in turn improve petroleum production. This method of temporarilyshutting off one or more production zones and reopening same may beuseful in the middle and/or later life of the well.

In embodiments where one conduit is placed inside the other, as shownfor example in FIGS. 4 to 6, the system may comprise additional ordifferent components and/or may be configured differently. Referring toFIG. 4, production conduit 20 extends axially along the length of theinner bore of injection conduit 18. Packers 16 are intermittentlypositioned on the outer surface and along the length of the injectionconduit 18 in the horizontal section of the well to fluidly seal theannulus between the wellbore inner surface and conduit 18 to definezones, as discussed above. At various locations along the length of bothconduits, seals 32 are provided to: (i) fluidly seal off a portion ofthe annulus between the outer surface of conduit 20 and the innersurface of conduit 18; and (ii) allow production conduit 20 tocommunicate with certain zones. Seals 32 are configured to haveproduction conduit 20 passing therethrough.

In one embodiment, each seal 32 has a first end, a second end, and aspace is provided therebetween. Seal 32 is positioned and installedrelative to the production conduit 20 such that at least one productionflow regulator 24 is situated in the space of the seal. Further, atleast one opening is provided in the injection conduit and the openingis in communication with the space of seal 32. The at least one openingin the injection conduit is preferably positioned axially between a pairof packers 16, and thus defining a production zone 28 in the annulusbetween the wellbore inner surface 11 and the outer surface of theinjection conduit and the pair of packers. The opening in the injectionconduit allows the passage of fluids between the space in seal 32 andthe zone.

Since flow regulator 24 is situated in the space of the seal, when it isin an open position, it is in fluid communication with the space of theseal and in turn the production zone 28. Seal 32 provides a fluid sealin the annulus between the conduits, thereby preventing any fluid in theinjection conduit from entering the space in the seal. Therefore, eachseal 32 allows fluid communication between the production zone and theproduction conduit 20, when flow regulator 24 is open, while preventingfluid communication between the injection conduit and the productionzone.

The system further comprises injection bypass tubes 30 to allow passageof fluid in the injection conduit through the seals 32, while bypassing(i.e. being fluidly sealed from) production zones. In a sampleembodiment, the bypass tube 30 extends between the first and second endsthrough each seal 32, allowing fluid communication between the annuliadjacent to the first and second ends while bypassing the space in seal32. Bypass tubes 30 thereby fluidly connect sections of the injectionconduit that are separated by seals 32 along the length of thehorizontal section, while bypassing production zones.

Accordingly, injection flow regulators 22 of the injection conduit aresituated in the zones that are not in communication with the productionconduit (i.e. zones without seals 32 positioned therein). Injectionfluid can flow past seals 32 to each flow regulator 22 along the lengthof the injection conduit via bypass tubes 30.

Seal 32 and injection bypass tube 30, together, allow fluidcommunication between the production zone and the production conduit,while allowing injection conduit fluid to bypass the production zone.

In another embodiment, the positions of the injection and productionconduits may be reversed, such that the injection conduit runs insidethe production conduit. In this embodiment, the fluid flow in eachconduit can also fluidly communicate with certain zones separately andindependently from the other conduit, through the use of seals 32 andinjection bypass tubes 30 as described above.

Referring to FIG. 5, the production conduit has an upper portion 20′ anda lower portion 20″. The injection conduit also has an upper portion 18′and a lower portion 18″. The relative position of the upper portions ofthe conduits to each other may be different than the relative positionof the lower portions down the length of the well. For example, theproduction conduit may be inside the injection conduit in the upperportion, while the production conduit houses the injection conduittherein in the lower portion.

In a sample embodiment shown in FIG. 5, the upper portion 20′ of theproduction conduit extends axially inside the length of the inner boreof the upper portion 18′ of the injection conduit in the substantiallyvertical section and the heel of the well. Below the heel, in thesubstantially horizontal section, the lower portion 18′ of the injectionconduit runs axially inside the lower portion 20′ of the productionconduit. In other words, the production conduit is the inner conduit inan upper part of the well and it is the outer conduit in a lower part ofthe well.

In the illustrated embodiment, the upper portion 20′ and lower portion20″ of the production conduit are connected by a transition bypass tube33, through which the upper portion 20′ and lower portion 20″ are influid communication.

Packers 16 are intermittently positioned on the outer surface and alongthe length of the lower portion 20″ of the production conduit to fluidlyseal the annulus between the wellbore inner surface and the outersurface of the production conduit to define zones, as discussed above.

At various locations along the length of both conduits 18″ and 20″ inthe horizontal section, seals 32′, 32″ are provided to: (i) fluidly sealoff a portion of the annulus between the outer surface of conduit 18″and the inner surface of conduit 20″; (ii) allow the lower portion 18″of the injection conduit to communicate with certain zones. Seals 32′,32″ are configured to have the lower portion 18″ of the injectionconduit passing therethrough.

In one embodiment, each seal 32′, 32″ has a first end, a second end, anda space is provided therebetween. Seal 32′, 32″ is positioned andinstalled relative to the lower portion 18″ of the injection conduitsuch that at least one injection flow regulator 22 is situated in thespace of the seal. Further, at least one opening is provided in thelower portion 20″ of the production conduit and the opening is incommunication with the space of seal 32′, 32″. The at least one openingin the lower portion 20″ is preferably positioned axially between a pairof packers 16, and thus defining an injection zone 26 in the annulusbetween the wellbore inner surface 11 and the outer surface of the lowerportion 20″ and the pair of packers. The opening in the lower portion20″ of the production conduit allows the passage of fluids between thespace of seal 32′, 32″ and the injection zone.

Since flow regulator 22 is situated in the space of the seal, when it isin an open position, it is in fluid communication with the space of theseal and in turn the injection zone 26. Seal 32′, 32″ provides a fluidseal in the annulus between the conduits, thereby preventing any fluidin the lower portion 20″ of the production conduit from entering thespace in the seal 32′, 32″. Therefore, each seal 32′, 32″ allows fluidcommunication between the injection zone and the lower portion 18″ ofthe injection conduit, when flow regulator 22 is open, while preventingfluid communication between the lower portion 20″ of production conduitand the injection zone.

In order to transition from the upper portions 18′ and 20′ to the lowerportions 18″ and 20″ of the conduits, transition bypass tube 33 fluidlyconnects the upper portion 20′ and the lower portion 20″ of theproduction conduit, to transition the production conduit from being theinner conduit to being the outer conduit. In one embodiment, transitionbypass tube 33 allows passage of fluid in the production conduit throughthe uppermost seal 32′, while bypassing the uppermost injection zone. Ina sample embodiment, the bypass tube 33 extends between the first andsecond ends through the uppermost seal 32′, allowing fluid communicationbetween the spaces adjacent to the first and second ends while bypassingthe space in the uppermost seal 32′. The upper end of bypass tube 33 isin communication with the upper portion 20′ of the production conduit(i.e. the inner conduit) and the lower end of bypass tube 33 is incommunication with the lower portion 20″ (i.e. the outer conduit),thereby transitioning the production conduit through the uppermost seal32′.

The upper portion 18′ of the injection conduit is in fluid communicationwith the lower portion 18″, for example via an opening in the lowerportion 18″ at or near the first end of the uppermost seal 32′, abovethe seal 32′.

Below the uppermost seal 32′, the system further comprises productionbypass tubes 34 to allow passage of fluid in the lower portion 20″ ofthe production conduit through the seals 32″, while bypassing injectionzones. In one embodiment, the bypass tube 34 extends between the firstand second ends through each seal 32″, allowing fluid communicationbetween the annuli adjacent to the first and second ends while bypassingthe space in seal 32″. Bypass tubes 34 thereby fluidly connect sectionsof the production conduit that are separated by seals 32″ along thelength of the horizontal section.

Accordingly, production flow regulators 24 of the production conduit aresituated in the zones that are not in communication with the injectionconduit (i.e. zones without seals 32′, 32″ positioned therein). Fluidsfrom the reservoir can enter the production conduit via each flowregulator 24 and flow up the production conduit through seals 32′, 32″via bypass tubes 33 and 34.

Seal 32′, 32″ and bypass tube 33, 34, together, allow fluidcommunication between the injection zone and the injection conduit,while allowing production conduit fluid to bypass the injection zone.The conduits are transitioned using transition bypass tube 33 anduppermost seal 32′, and are maintained using production bypass tubes 34and seals 32″, such that fluid flow in upper portion 20′ and lowerportion 20″ of the production conduit is separated from fluid flow inupper portion 18′ and lower portion 18″ of the injection conduitthroughout the length of the well.

In another embodiment, the positions of the injection and productionconduits may be reversed, such that the upper portion of the injectionconduit runs inside the upper portion of the production conduit and thelower portion of the production conduit runs inside the lower portion ofthe injection conduit. In this embodiment, the fluid flow in eachconduit can also fluidly communicate with certain zones separately andindependently from the other conduit, through the use of seals 32′, 32″and bypass tubes 33 and 34 as described above.

In another sample embodiment, as shown in FIG. 6, a cased well includescasing 14 which is cemented to wellbore wall 10 in at least thehorizontal section. Casing 14 may have a larger diameter segment abovethe heel of the well that extends to surface, and an uncemented tubingis placed in the larger diameter segment. The wellbore inner surface 11in the horizontal section is the inner surface of casing 14 in thehorizontal section. In this embodiment, rather than providing a separatetubing for injection conduit 18, injection conduit 18 is defined by thewellbore inner surface 11. Instead of injection flow regulators andproduction flow regulators, a plurality of casing flow regulators 23 areprovided at or near the outer surface of casing 14, intermittentlypositioned along the length of the horizontal section of the well. Eachof the flow regulators 23 is in communication with at least one fractureF in the formation 8.

In one embodiment, casing flow regulators 23 function as both hydraulicfracture diversion valves and as injection flow regulators (as describedabove) or production flow regulators (as described above). Each casingflow regulator may be remotely and/or independently operated. Eachcasing flow regulator has an open position and a closed position, andthe open position may include one or more partially open positions (e.g.screened, choked, etc.). In the open position, the casing flow regulator23 permits communication between the horizontal section of the wellboreand the fracture through a perforation in casing 14. In the closedposition, casing flow regulator 23 blocks fluid flow therethrough.

Production conduit 20 extends axially along the length of the inner boreof injection conduit 18, which is in the horizontal section of thewellbore defined by wellbore inner surface 11. Packers 16′ areintermittently positioned on the outer surface and along the length ofthe production conduit 20 in the horizontal section of the well tofluidly seal the annulus between the wellbore inner surface and conduit20 to define zones, as discussed above. In this embodiment, packers 16′are also provided to allow production conduit 20 to communicate withcertain zones, while allowing fluid in the injection conduit 18 tobypass these zones.

In one embodiment, each packer 16′ has a first end packer, a second endpacker. The end packers ate separated by a space therebetween. Packer16′ is positioned and expanded (i.e. installed) relative to casing 14 inthe horizontal section such that at least one casing flow regulator 23is situated in the space in between the end packers of the packer 16′.The at least one casing flow regulator 23 therefore allows fluidcommunication between the fracture(s) connected thereto and the space inpacker 16′, when the casing flow regulator is in an open position.

Further, at least one opening is provided in the production conduit 20and the at least one opening is in fluid communication with the space ofpacker 16′. Thus, the space in packer 16′ defines a production zone 28,in which reservoir fluids may be collected when the at least one casingflow regulator 23 in the production zone is open or partially open. Anyfluid collected in the production zone 28 can flow into the productionconduit 20 through the at least one opening therein. Packer 16′ providesa fluid seal in the annulus between the conduits, thereby preventing anyfluid in the injection conduit from entering the production zone.Therefore, each packer 16′ allows fluid communication between at leastone fracture and the production conduit 20, when the casing flowregulator in the production zone is open or partially open, whilepreventing fluid communication between the injection conduit and theproduction zone.

Packers 16′ are also spaced apart along the production conduit 20, andpositioned and expanded relative to casing 14 in the horizontal section,such that at least one casing flow regulator 23 is situated between atleast a pair of adjacent packers 16′, thereby defining an injection zone26 between the pair of packers 16′ with which at least one fracture canfluidly communicate through the at least one casing flow regulator 23when the regulator is open or partially open.

The system further comprises injection bypass tubes 30′ to allow passageof fluid in the injection conduit between injection zones 26 through thepackers 16′, while bypassing (i.e. being fluidly sealed from) productionzones 28. In one embodiment, the bypass tube 30′ extends between thefirst and second ends through each packer 16′, allowing fluidcommunication between the injection zone adjacent to the first endpacker and the injection zone adjacent the second end packer whilebypassing the production zone in packer 16′. Bypass tubes 30′ therebyfluidly connect sections of the injection conduit that are separated bypackers 16′ along the length of the horizontal section.

Packers 16′ and injection bypass tube 30′, together, allow fluidcommunication between the production zone and the production conduit,while allowing injection conduit fluid to bypass the production zone.

In another embodiment, the positions of the injection and productionconduits may be reversed, such that the injection conduit runs insidethe production conduit. In this embodiment, the fluid flow in eachconduit can also fluidly communicate with certain zones separately andindependently from the other conduit, through the use of packers 16′ andinjection bypass tubes 30′ as described above.

In one embodiment, any of the above-discussed bypass tubes withreference to FIGS. 4 to 6 may be a non-circular tube. For example, theinjection bypass tube may have a rectangular cross-section. Othercross-sectional shapes are possible. Referring to the sample embodimentshown FIGS. 6, 10 a and 10 b, the injection bypass tube 30′ is has anarc-shaped cross-section, and the bypass tube has substantiallyconcentric inner and outer arc segment shaped walls with differentradii. The inner and outer arc segment shaped walls are connected at thelengthwise sides by flat walls. In this sample embodiment, the bypasstube 30′ is disposed outside the production conduit and extends axiallythrough the production zone 28.

Referring to FIGS. 6, 11 a and 11 b, another sample embodiment is shownwherein the bypass tube 30′ is disposed eccentrically outside theproduction conduit 20 and surrounds a lengthwise portion of theproduction conduit. In this embodiment, a portion of the outer surfaceof the production conduit 20 is in contact with the inner surface of thebypass tube 30′. An opening extends between the inner surface of theproduction conduit and the outer surface of the bypass tube, therebyallowing fluid communication between the inside of the productionconduit and the production zone 28. In this sample embodiment, theeffective cross-sectional shape of the bypass tube is the crescent shapeof the space defined by the outer surface of the production conduit andthe inner surface of the bypass tube where the two tubes are not incontact.

FIG. 8 illustrates another sample embodiment for use with a cased wellhaving a casing 14 which is cemented to wellbore wall 10 in at least thehorizontal section. The wellbore inner surface 11 is the inner surfaceof casing 14. In this embodiment, rather than having two separatetubings for injection and production, one conduit 19 is provided fortransporting both injection fluid and reservoir fluid therein.Therefore, in this embodiment, the injection conduit and the productionconduit are one and the same. Conduit 19 extends down the well throughthe heel to near or past the beginning of the horizontal section.

Further, instead of injection flow regulators and production flowregulators, a plurality of casing flow regulators 23 are provided at ornear the outer surface of casing 14, intermittently positioned along thelength of the horizontal section of the well. Each of the flowregulators 23 is in communication with at least one fracture F in theformation 8.

Conduit 19 has at least one opening 42 at or near its lower end forpassage of fluids therethrough, thereby allowing fluid communicationbetween the conduit and the wellbore. In one embodiment, opening 42 mayinclude a flow regulator to allow selective opening and closing thereof.

In one embodiment, casing flow regulators 23 function as both hydraulicfracture diversion valves and as injection flow regulators (as describedabove) or production flow regulators (as described above). Each casingflow regulator may be remotely and/or independently operated. Eachcasing flow regulator has an open position and a closed position, andthe open position may include one or more partially open positions (e.g.screened, choked, etc.). In the open position, the casing flow regulator23 is in communication with the horizontal section of the wellborethrough an opening in casing 14. In the closed position, casing flowregulator 23 blocks fluid flow therethrough. Each casing flow regulator23 therefore allows fluid communication between the fracture(s)connected thereto and the wellbore, when the casing flow regulator is inan open position.

Accordingly, when any one of the casing flow regulators 23 is open andwhen the opening 42 in the conduit 19 is open, conduit 19 is in fluidcommunication via the wellbore with the fracture(s) connected to theopen casing flow regulator(s).

In operation, the system in the sample embodiment shown in FIG. 8 allowsasynchronous injection into and production from a well using only oneconduit. For example, injection fluid is pumped down conduit 19 andflows through opening 42 into the wellbore. Some of the casing flowregulators 23 are then opened, while others are kept closed, so that theinjection fluid in the wellbore can flow through the open casing flowregulators into the fractures connected thereto.

Once the desired amount of injection fluid has been injected into thewellbore, the pumping of injection fluid down conduit 19 is stopped. Inone embodiment, the open casing flow regulators 23 are closed and thecasing flow regulators that were closed during the injection ofinjection fluid are then opened to allow reservoir fluid to flowtherethrough, from the fractures connected to the casing flow regulatorsinto the wellbore. In another embodiment, one or more of the previouslyopened flow regulators may be left open and one or more of thepreviously closed flow regulators may be opened or left closed. If theopening 42 in conduit 19 is open, reservoir fluid in the wellbore canflow through the opening 42 and be collected in conduit 19 fortransportation to surface.

Referring to FIG. 9, a sample embodiment is shown wherein one conduit19′ is provided for transporting both injection fluid and reservoirfluid therein. Therefore, in this embodiment, the injection conduit andthe production conduit are one and the same. This embodiment is usablewith a cased well having a casing 14 which is cemented to wellbore wall10 in at least the horizontal section. Here, the wellbore inner surface11 is the inner surface of casing 14. Conduit 19′ extends down the wellthrough the heel and into at least a portion of the horizontal section.

Further, instead of injection flow regulators and production flowregulators, a plurality of flow regulators 44 are provided in conduit19, intermittently positioned along the length of the conduit. Flowregulators 44 function as injection flow regulators (as described above)and/or production flow regulators (as described above). Each flowregulator 44 may be remotely and/or independently operated. Each flowregulator 44 has an open position and a closed position, and the openposition may include one or more partially open positions (e.g.screened, choked, etc.). In the open position, the flow regulator 44allows fluid to flow therethrough into or out of conduit 19. In theclosed position, the flow regulator 44 blocks fluid flow therethrough.

Conduit 19′ extends axially along the horizontal section of the wellboredefined by wellbore inner surface 11. Packers 16 are intermittentlypositioned on the outer surface and along the length of the conduit 19′.Preferably, Packers 16 are positioned on conduit 19′ such that at leastone flow regulator 44 is situated in between each pair of adjacentpackers 16. Further, adjacent packers 16 are positioned and expanded(i.e. installed) relative to the perforations 13 in casing 14 in thehorizontal section such that at least one perforation 13 is situated inbetween at least a pair of adjacent packers 16. In this manner, packers16 are provided and positioned in the horizontal section of the well tofluidly seal the annulus between the wellbore inner surface and conduit19 to define zones, as discussed above. The zones are fluidly sealedfrom one another inside the horizontal section but can fluidlycommunicate with one another via the conduit 19′.

In this embodiment, each zone is in communication with at least onefracture, via at least one perforation 13, and is communicable withconduit 19 via at least one flow regulator 44. The flow regulator 44 ineach zone therefore allows fluid communication between the fracture(s)connected to the zone and conduit 19′, when the flow regulator 44 is inan open position. In the closed position, flow regulator 44 blocks fluidcommunication between the fracture(s) connected to the zone and theconduit 19′. One zone can fluidly communicate with another zone if theflow regulators 44 in the zones are open.

In operation, the system in the sample embodiment shown in FIG. 9 allowsasynchronous injection into and production from a well using only oneconduit. For example, injection fluid is pumped down conduit 19′ and oneor more of the flow regulators 44 are then opened so that the injectionfluid can flow out of the open flow regulators through the zones inwhich the open flow regulators are situated and into the fracturesconnected those zones.

Once the desired amount of injection fluid has been injected into theformation, the pumping of injection fluid down conduit 19′ is stopped.In one embodiment, the open flow regulators are closed and the flowregulators that were closed during the injection process are opened.Alternatively, some of the open flow regulators may be left open and oneor more of the previously closed flow regulators may be opened or leftclosed. Any reservoir fluid from the formation flowing into the zonesthrough the fractures is collected in the conduit 19′ via the open flowregulators 44. The collected reservoir fluid in conduit 19′ is thentransported to surface, as discussed above.

The system of the present invention may employ instrumentation to helpmonitor the injection and/or production zone environment, which allowsspecific controls to be applied in order to manage the above-describedinjection-production method. The instrumentation may include for examplemeasurement devices for monitoring fluid properties and pressure ortemperature conditions at each production or injection zone. Theinstrumentation may also be used to monitor the health of the systemincluding for example, whether packers are sealing properly, whether thecasing cement is isolating annular injection flow into the fractures oris allowing short-circuiting such as through an annulus cement channelbetween an injection zone and an adjacent production zone, and to helpidentify the location of a leak in a flow conduit or an improperlyfunctioning flow regulator.

In one embodiment, a device for monitoring the concentration of theinjection fluid in the petroleum being produced in the wellbore isinstalled adjacent to the fractures in one or more of the productionzones. Examples of such measurement and monitoring devices include forexample fluid flow meters, electric resistivity devices, oxygen decaymonitoring devices, fluid density monitoring devices, pressure gaugedevices, and temperature monitoring devices that obtain measurements atdiscrete locations, or distributed measurement devices such as fiberoptic sensors to measure distributed temperature, distributed acousticsoundfield, chemical composition, pressure, etc. Data from these devicescan be obtained through electric lines, fiber-optic cables, retrieval ofbottom hole sensors, in well interrogation of the devices usinginduction coupling or other methods common in the industry.

In another embodiment, a sampling line is installed into the productionconduit. The sampling line may be a tubing (coiled or jointed) thattakes a sample of the fluid in one or more production zones. In yetanother embodiment, a sampling chamber is formed in one or moreproduction zones so that discrete samples of fluid can be taken.

With the above-described devices and monitoring techniques, theproportion of injection fluid in reservoir petroleum can be estimated ormeasured for any particular production zone to help with determining,for example: (i) when to stop injecting fluid into the well; (ii) whento stop injecting fluid into one or more zones of the well; and/or (iii)when to stop producing one or more zones of the well.

The system may also be in communication with well logging devices, andseismic or active sonar imaging devices for measuring the progress ofsweeping by, for example, fiber optic acoustic detection of the echoproduced by a sound pulse originating at the wellbore and analysis ofthe returned echo waveform properties to infer distance to reservoirboundaries or heterogeneities including natural or hydraulic fracturesor the general fluid composition in the reservoir through which thesound pulse traveled.

Instrumentation that may be used with the system includes for example,fiber optic distributed temperature sensors (DTS), fiber opticdistributed acoustic sensors (DAS), fiber optic distributed pressuresensors (DPS), fiber optic distributed chemical sensors (DCS), andpermanent downhole gauges (PDGs).

A DTS may be used with the system to measure the temperature inside oroutside the casing string at along its length in real time. Additionallyor alternatively, a DAS may be used to measure the sound environmentinside the horizontal wellbore section along its length in real time.Additionally or alternatively, a DPS may be used to measure the pressureinside the horizontal wellbore section continuously orpseudo-continuously at a multitude of discrete points along its lengthin real time. In a sample embodiment, both DTS and DAS are housedtogether in a separate stainless steel control line runningsubstantially the full length of the production conduit.

In a further embodiment, PDGs are used at each injection and/orproduction zone to electronically measure the pressure and temperaturetherein, and an electric cable is used to provide power to each gaugeand/or to transmit signal data to the surface. In a sample embodiment,the PDGs are fiber optic devices which optically measure bothtemperature and pressure at discrete points within the well and may usean optic fiber to optically convey the measurement signal to surface. Asingle cable may be used for each gauge or for a plurality of gauges.

Downhole separation of gas from the produced petroleum may beaccomplished using a downhole separator to separate the gas from theproduced petroleum in the production conduit. The separator may be, forexample, a cyclone-type or hydrocyclone-type separator. The separationmay be followed by compression of the collected gas to the pressure ofthe injection fluid in the injection conduit, and the compression may beachieved by a centrifugal compressor or a reciprocating compressor. Thecompressed collected gas may be supplied to the injection conduit asinjection fluid. The separator may include an electric submersible orprogressing cavity pump, which may be used to impart energy into theproduced fluid to help lift the fluid to surface.

Referring to the sample embodiments shown in FIGS. 6 and 8, measurementand control system instrumentation including for example pressuregauges, fiber optic sensors, and hydraulic and electric control lines39, etc. may be installed outside casing 14 (i.e. between wellbore innersurface 11 and wellbore wall 10). Alternatively or additionally, theflow regulators 23 may be controlled with radio-frequency identification(RFID). Alternatively or additionally, measurement system componentsincluding gauges and fiber optic sensors may be installed on or near theouter surface of the production conduit 20. The placement of the casingflow regulators and/or instrumentation outside the casing may helpreduce the complexity of the required downhole tubing equipment for theconduits.

With respect to the above-described injection-production system, thereis provided a method of enhancing petroleum production from a wellhaving a well section with a wellbore inner surface in communicationwith a plurality of fractures in a formation containing reservoir fluid,the method comprising: creating a first set and a second set of zones inthe well section, each zone for communicating with at least one of theplurality of fractures, and the first set of zones being fluidly sealedfrom the second set of zones in the well section; and selectivelyinjecting injection fluid into the formation via at least one zone inthe first set of zones. The method further comprises selectivelycollecting reservoir fluid from the formation via at least one zone inthe second set of zones; and transporting the collected reservoir fluidto surface.

At least some of the fractures associated with the first set of zonesare in direct or indirect fluid communication with at least some of thefractures associated with the second set of zones. The fracturescommunicable with the first set of zones are not necessarily distinctfrom the fractures communicable with the second set. Also, the zones inthe first set are not necessarily distinct from the zones in the secondset. There may be overlaps in the two sets of zones, such that any onezone can be in both the first set and the second set. In other words,any one zone of either set may function as one or both of an injectionzone and a production zone. Further, each set of zones may contain oneor more zones.

In one embodiment, the method comprises: running a production conduitand an injection conduit down the well, the production conduit or theinjection conduit having installed thereon packers in the retractedposition; expanding the packers to engage the wellbore inner surface tofluidly seal the annulus between the outer surface of the conduits andthe wellbore inner surface to define at least one injection zone betweena pair of adjacent packers and at least one production zone betweenanother pair of adjacent packers. The at least one injection zone is incommunication with at least one fracture and the at least one productionzone is also in communication with at least one fracture.

The method further comprises supplying injection fluid to the injectionconduit. The injection fluid may be supplied from a supply source atsurface. Alternatively or additionally, injection fluid may be recoveredand separated from the produced fluids in the production conduit,compressed, and then re-injected into the injection conduit. In oneembodiment, any or all of the recovering, separating, compressing, andre-injecting of injection fluid may be performed downhole.

The method further comprises selectively injecting injection fluid intoone of the at least one injection zone. In one embodiment, the pressureat which injection fluid is injected into the injection zones rangesbetween the minimum miscibility pressure of the target reservoir fluidand the minimum hydraulic fracture propagating pressure of the targetreservoir formation. Minimum miscibility pressure may be determined in alab by re-pressurizing a sample of the reservoir fluid. The sample isobtained and analyzed using a specific process known as PVT testing. Asthe injection fluid is pumped into the reservoir via the fractures inthe injection zones, a pressure gradient is created in the reservoirbetween the injection and production zones, resulting in flow in thedirection of the pressure gradient from the injection zones to theproduction zones. The flood of injection fluid into the reservoir causesthe pressure of the reservoir to rise to at least above the minimummiscibility pressure of the petroleum in the reservoir, thereby trappingotherwise free gas in solution, which results in a higher relativepermeability of the petroleum in the formation. In one embodiment, adissolvable injection fluid is injected into the fractures to increasethe mobility of the reservoir petroleum in order to help improve theproduction rate. Petroleum in the reservoir moves through the fracturesand into the production zones.

The method further comprises selectively collecting reservoir fluid(including petroleum) from one of the at least one production zone intothe production conduit. The method may further comprise transporting thereservoir fluid in the production conduit to surface. As discussedabove, the reservoir fluid may be transported by pumping and/or gaslifting.

The selective injection of injection fluid may be accomplished byopening or closing at least one injection flow regulator of theinjection conduit in the one of the at least one injection zone. Theselective collection of reservoir fluid may be accomplished by openingor closing at least one production flow regulator of the productionconduit in the one of the at least one production zone.

In one embodiment, the injection of injection fluid into the at leastone injection zone occurs substantially simultaneously as the collectionof reservoir fluid from the at least one production zone. In anotherembodiment, the injection of injection fluid and the collection ofreservoir fluid occur asynchronously, such that there is substantiallyno simultaneous flow in both conduits. Injection fluid may becontinuously, periodically, or sporadically pumped into the reservoirvia the injection zones.

The production zones may or may not all flow at the same time. Forexample, one or more production zones may be selectively shut off fromcollecting reservoir fluid temporarily or permanently. As mentionedabove, by shutting off one or more production zones for a certain periodof time, the injection fluid is allowed to penetrate deeper into thereservoir which may help increase petroleum production. In a furtherembodiment, selected production zones may be shut off while theremaining production zones are open and allowed to produce petroleum,and the pattern or sequence of which production zones are opened or shutoff at any given time may be configured as required to optimize theperformance of the system.

In another embodiment, a method for enhancing petroleum production froma well having a wellbore with a wellbore inner surface, the wellborecommunicable via the wellbore inner surface with a first set and asecond set of fractures in a formation containing reservoir fluid, themethod comprising: supplying injection fluid to the wellbore via aconduit; injecting injection fluid from the wellbore to the formationthrough the first set of fractures, while blocking fluid flow to andfrom the second set of fractures; ceasing the supply of injection fluid;blocking fluid flow to and from the first set of fractures; permittingflow of reservoir fluid from the formation through the second set offractures into the wellbore; and collecting reservoir fluid from thewellbore via the conduit.

At least some of the fractures of the first set are in direct orindirect fluid communication with at least some of the fractures of thesecond set through the formation. The fractures in the first set are notnecessary distinct from the fractures in the second set. There may beoverlaps in the fractures of the two sets. Also, each set of fracturescontains one or more fractures.

Another method for producing petroleum involves using a plurality ofinjection-production systems together to influence inter-well reservoirregions to allow sweeping between fractures that originate fromdifferent wellbores. For example, the injection-production system may beused for separate wells with alternating fracture positions, asillustrated in FIG. 7. A fractured well 40 a is near at least one otherfractured well 40 b. Well 40 b may be spaced apart from well 40 a in anydirection, including for example lateral, diagonal, above, below, or acombination thereof. The long axes of the wells may or may not beparallel to each other, and may or may not share the same plane. Each ofthe wells 40 a and 40 b has the above described injection-productionsystem installed therein.

Some of the fractures of well 40 a may be in close proximity to some ofthe fractures of well 40 b and may extend between some of the fracturesof well 40 b, and vice versa. Because of the proximity of some of thefractures between the two wells, cross flows may occur therebetween, asindicated by the arrows “C”. More specifically, for example, some of theinjection fluid injected into well 40 b may flow out of the fracturestoward the fractures of well 40 a, which may sweep petroleum in thereservoir to flow into the production zones of well 40 a. Similarly,some of the injection fluid injected into well 40 a may flow out of thefractures toward the fractures of well 40 b, which may sweep petroleumin the reservoir to flow into the production zones of well 40 b. Thesecross flows C may enhance petroleum production by allowing moreextensive sweeping of the reservoir, which might not be possible withonly one fractured well.

In one embodiment, injection fluid is injected into both wells 40 a and40 b in order to produce reservoir petroleum from both wells. In anotherembodiment, injection fluid is injected into only one well and petroleumis produced from both wells. In yet another embodiment, injection fluidis injected into only one well and petroleum is produced from the otherwell. In a further embodiment, the injection of injection fluid into thewells and/or the production of petroleum from the wells may beselectively turned on and off to alternate the pattern of injectionand/or production between the wells. Of course, other injection and/orproduction patterns and sequences are also possible.

In addition, there may be more than two adjacent fractured wells havingthe injection-production system, such that one well may provide crossflows to one or more adjacent wells. The plurality of wells may beoriented in many different directions relative to one another and theinjection and/or production patterns and sequences of the plurality ofwells can be selectively modified and controlled, as described abovewith respect to wells 40 a and 40 b.

While the above description refers to wells with a substantiallyhorizontal section, the present invention may be applied to verticalwells and/or deviated wells.

The above described intra-well enhanced recovery methods and systems mayhave advantages over a conventional inter-well line drive scheme. Forexample, the present invention may lead to rapid response to fluidinjection due to smaller spacing between injection and production zones.In addition, the present invention may allow simultaneous injection andproduction in the same wellbore without the need of converting theentire wellbore for only injection. Therefore, the present invention maylead to greater hydrocarbon recovery due to a combination of highmicroscopic sweep efficiency particularly with the injection of amiscible solvent gas and high areal sweep efficiency of a line drivepattern. Additional advantages may include pressure maintenance tolessen reservoir pressure decline and resulting gas lift of liquidhydrocarbon in the wellbore due to solvent gas injection which typicallycommences after a short period of primary recovery to allow for highinitial production and better injectivity with some reservoir pressuredepletion.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to those embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein, but is to beaccorded the full scope consistent with the claims, wherein reference toan element in the singular, such as by use of the article “a” or “an” isnot intended to mean “one and only one” unless specifically so stated,but rather “one or more”. All structural and functional equivalents tothe elements of the various embodiments described throughout thedisclosure that are known or later come to be known to those of ordinaryskill in the art are intended to be encompassed by the elements of theclaims. Moreover, nothing disclosed herein is intended to be dedicatedto the public regardless of whether such disclosure is explicitlyrecited in the claims. For US patent properties, it is noted that noclaim element is to be construed under the provisions of 35 USC 112,sixth paragraph, unless the element is expressly recited using thephrase “means for” or “step for”.

1. A method for petroleum production from a well having a well sectionwith a wellbore inner surface in communication with a plurality offractures in a formation containing reservoir fluid, the methodcomprising: creating a first set and a second set of zones in the wellsection, each zone for communicating with at least one of the pluralityof fractures, and the first set of zones being fluidly sealed from thesecond set of zones in the well section; and selectively injectinginjection fluid into the formation via at least one zone in the firstset of zones.
 2. The method of claim 1 further comprising: selectivelycollecting reservoir fluid from the formation via at least one zone inthe second set of zones; and transporting the collected reservoir fluidto surface.
 3. The method of claim 2, wherein each zone is associatedwith a flow regulator, the flow regulator having an open position whichallows fluid flow therethrough and a closed position which blocks fluidflow therethrough, for controlling one or both of: (i) flow of fluidinto the zone; and (ii) flow of fluid out of the zone.
 4. The method ofclaim 3, wherein the flow regulator associated with the at least onezone in the first set of zones is in communication with a supply ofinjection fluid, and further comprising selectively injecting injectionfluid by selectively opening the flow regulator associated with the atleast one zone in the first set of zones.
 5. The method of claim 3,wherein the flow regulator associated with the at least one zone in thesecond set of zones allows at least some of the reservoir fluid to passtherethrough in the open position, and further comprising selectivelycollecting reservoir fluid by selectively opening the flow regulatorassociated with the at least one zone in the second set of zones.
 6. Themethod of claim 2, wherein the collected reservoir fluid is transportedto surface by one or more of: pumping and gas-lifting.
 7. The method ofclaim 3, wherein the flow regulator preferentially allows the flow ofpetroleum therethrough.
 8. The method of claim 4, wherein the supply ofinjection fluid flows through a conduit extending along the wellsection.
 9. The method of claim 5, wherein the flow regulator is incommunication with a conduit extending from surface into the wellsection, and further comprising permitting reservoir fluid in the atleast one zone in the second set to flow into the conduit andtransporting the collected reservoir within the conduit.
 10. The methodof claim 3, wherein the flow regulator is in communication with aconduit extending from surface into the well section, further comprisingsupplying injection fluid through the conduit; and selectively injectinginjection fluid by selectively opening the flow regulator associatedwith the at least one zone in the first set of zones.
 11. The method ofclaim 10, further comprising ceasing the supply of injection fluid;selectively collecting reservoir fluid by selectively opening the flowregulator associated with the at least one zone in the second set ofzones; permitting reservoir fluid in the at least one zone in the secondset to flow into the conduit and transporting the collected reservoirwithin the conduit.
 12. The method of claim 1, wherein packers are usedto fluidly seal the zones from one another.
 13. The method of claim 2,wherein injecting injection fluid and collecting reservoir fluid occursimultaneously.
 14. The method of claim 2, wherein injecting injectionfluid and collecting reservoir fluid occur asynchronously.
 15. Themethod of claim 2, wherein a portion of the injection fluid is recoveredfrom the collected reservoir fluid.
 16. A method for hydrocarbonproduction from a well having a well section with a wellbore innersurface in communication with a first set and a second set of fracturesin a formation containing reservoir fluid, the method comprising:creating a plurality of injection zones in the well section, eachinjection zone for communicating with at least one fracture in the firstset of fractures at the wellbore inner surface; creating a plurality ofproduction zones in the well section, each production zone forcommunicating with at least one fracture in the second set of fracturesat the wellbore inner surface and for receiving reservoir fluid from theformation via the at least one fracture in the second set of fractures,each production zone being fluidly sealed from the injection zonesinside the well section; selectively injecting injection fluid into theformation via at least one of the injection zones; selectivelycollecting reservoir fluid from the formation via at least one of theproduction zones; and transporting the collected reservoir fluid tosurface.
 17. The method of claim 16, wherein each injection zone is incommunication with an injection flow regulator, the injection flowregulator being in communication with a supply of injection fluid, andfurther comprising selectively injecting injection fluid by selectivelyopening the injection flow regulator in communication with the at leastone of the injection zones.
 18. The method of claim 16, wherein eachproduction zone is in communication with a production flow regulator,and further comprising selectively collecting reservoir fluid byselectively opening the production flow regulator in communication withthe at least one of the production zones and allowing at least some ofthe reservoir fluid to pass through the production flow regulator. 19.The method of claim 17, wherein the supply of injection fluid flowsthrough an injection conduit extending along the well section.
 20. Themethod of claim 18, wherein the production flow regulator is incommunication with a production conduit extending from the well sectionto surface, and the collected reservoir fluid is transported within theproduction conduit.
 21. The method of claim 16, wherein injectinginjection fluid and collecting reservoir fluid occur simultaneously. 22.The method of claim 16, wherein injecting injection fluid and collectingreservoir fluid occur asynchronously.
 23. A method for petroleumproduction involving a first well having a first well section with afirst wellbore inner surface in communication with a first set offractures in a formation containing reservoir fluid and a second wellhaving a second well section with a second wellbore inner surface incommunication with a second set of fractures in the formation, whereinsome of the fractures in the first set are in close proximity to some ofthe fractures in the second set, the method comprising: creating aplurality of injection zones in the first well section, each injectionzone for communicating with at least one of the fractures in the firstset that are in close proximity to some of the fractures in the secondset, via the first wellbore inner surface; creating a plurality ofproduction zones in the second well section, each production zone forcommunicating with at least one of the fractures in the second set thatare in close proximity to some of the fractures in the first set, viathe second wellbore inner surface, the plurality of production zonesconfigured to receive reservoir fluid from the formation; selectivelyinjecting injection fluid into the formation via at least one of theinjection zones; selectively collecting reservoir fluid from theformation via at least one of the production zones; and transporting thecollected reservoir fluid to surface.
 24. The method of claim 23,wherein some of the fractures in the first set that are in closeproximity to some of the fractures in the second set extend between someof the fractures in the second set.
 25. The method of claim 23, whereineach injection zone is in communication with an injection flow regulatorhaving an open position which allows fluid flow therethrough and aclosed position which blocks fluid flow therethrough, the injection flowregulator being in communication with a supply of injection fluid, andfurther comprising selectively injecting injection fluid by selectivelyopening the injection flow regulator in communication with the at leastone of the injection zones.
 26. The method of claim 23, wherein eachproduction zone is in communication with a production flow regulatorhaving an open position which allows at least some reservoir fluid toflow therethrough and a closed position which blocks fluid flowtherethrough, and further comprising selectively collecting reservoirfluid by selectively opening the production flow regulator incommunication with the at least one of the production zones.
 27. Themethod of claim 23, wherein the collected reservoir fluid is transportedto surface by one or more of: pumping and gas-lifting.
 28. The method ofclaim 26, wherein the production flow regulator preferentially allowsthe flow of petroleum therethrough.
 29. The method of claim 25, whereinthe supply of injection fluid flows through a conduit extending alongthe first well section.
 30. The method of claim 26, wherein theproduction flow regulator is in communication with a conduit extendingfrom the second well section to surface, and further comprisingcollecting reservoir fluid from the at least one of the production zonesinto the conduit and transporting the collected reservoir fluid withinthe conduit.
 31. The method of claim 23, wherein injecting injectionfluid and collecting reservoir fluid occur simultaneously.
 32. Themethod of claim 23, wherein injecting injection fluid and collectingreservoir fluid occur asynchronously.
 33. The method of claim 23,wherein a portion of the injection fluid is recovered from the collectedreservoir fluid.
 34. A system for petroleum production from a wellhaving an inner bore and a well section with a wellbore inner surface incommunication with a first set and a second set of fractures in aformation containing reservoir fluid, the system comprising: aninjection conduit extending inside the inner bore and along at leastpart of the well section; a production conduit extending inside theinner bore and along at least part of the well section; at least oneinjection zone in the well section for communicating with at least onefracture in the first set of fractures at the wellbore inner surface; atleast one production zone in the well section for communicating with atleast one fracture in the second set of fractures at the wellbore innersurface, the at least one production zone being fluidly sealed from theat least one injection zone inside the well section; at least oneinjection flow regulator in association with the at least one injectionzone, the at least one injection flow regulator having an open positionwhich allows fluid communication between the injection conduit and theat least one fracture in the first set of fractures via the at least oneinjection zone, and a closed position which blocks fluid communicationbetween the injection conduit and the at least one fracture in the firstset of fractures; and at least one production flow regulator inassociation with the at least one production zone, the at least oneproduction flow regulator having an open position which allows fluidcommunication between the production conduit and the at least onefracture in the second set of fractures via the at least one productionzone, and a closed position which blocks fluid communication between theinjection conduit and the at least one fracture in the second set offractures.
 35. The system of claim 34 wherein the production conduit andthe injection conduit are positioned side-by-side axially in the wellsection.
 36. The system of claim 34 wherein one of the production andinjection conduits is inside the other conduit in the well section, theconduit on the inside being an inside conduit and the conduit on theoutside being an outside conduit.
 37. The system of claim 34 wherein theat least one injection flow regulator is connected to the injectionconduit.
 38. The system of claim 34 wherein the at least one productionflow regulator is connected to the production conduit.
 39. The system ofclaim 34 further comprising packers for fluidly sealing the at least oneproduction zone from the at least one injection zone.
 40. The system ofclaim 34 wherein the well section includes a casing with an outersurface and an inner surface, the inner surface being the wellbore innersurface, and wherein the at least one production flow regulator and theat least one injection flow regulator are installed on the outer surfaceof the casing or outside of the casing adjacent the outer surfacethereof.
 41. The system of claim 36 further comprising a bypass tubeextending through and bypassing the at least one production zone, andfluidly connecting the at least one injection zone with anotherinjection zone.
 42. The system of claim 36 further comprising a bypasstube extending through and bypassing the at least one injection zone,and fluidly connecting the at least one production zone with anotherproduction zone.
 43. The system of claim 36 wherein the wellbore innersurface in the well section defines the outside conduit.
 44. The systemof claim 40 further comprising measurement and control systeminstrumentation which is installed outside of the casing adjacent theouter surface thereof.
 45. The system of claim 36 further comprising aseal and a bypass tube, the bypass tube extending through the sealbetween a first end and a second end of the seal, the seal allowingfluid communication between the inner conduit and a zone, and the bypasstube bypassing the zone and fluidly connecting sections of the outerconduit adjacent to the first and second ends of the seal.
 46. Thesystem of claim 34 wherein the production conduit and the injectionconduit are one and the same.
 47. A method for producing petroleum froma well having a wellbore with a wellbore inner surface, the wellborecommunicable via the wellbore inner surface with a first set and asecond set of fractures in a formation containing reservoir fluid, themethod comprising: supplying injection fluid to the wellbore via aconduit; injecting injection fluid from the wellbore to the formationthrough the first set of fractures, while blocking fluid flow to andfrom the second set of fractures; ceasing the supply of injection fluid;blocking fluid flow to and from the first set of fractures; permittingflow of reservoir fluid from the formation through the second set offractures into the wellbore; and collecting reservoir fluid from thewellbore via the conduit.
 48. The method of claim 47, wherein the firstset of fractures and the wellbore is fluidly communicable through atleast one flow regulator having an open position which allows fluid flowtherethrough and a closed position which blocks fluid flow therethrough,and further comprising opening the at least one flow regulator to injectinjection fluid to the formation through the first set of fractures; andclosing the at least one flow regulator to block fluid flow to and fromthe first set of fractures.
 49. The method claim 47, wherein the secondset of fractures and the wellbore is fluidly communicable through atleast one flow regulator having an open position which allows fluid flowtherethrough and a closed position which blocks fluid flow therethrough,and further comprising closing the at least one flow regulator to blockfluid flow to and from the second set of fractures; and opening the atleast one flow regulator to permit flow of reservoir fluid from theformation through the second set of fractures into the wellbore.
 50. Themethod of claim 47, wherein the collected reservoir fluid is transportedto surface by one or more of: pumping and gas-lifting.
 51. The method ofclaim 47, wherein a portion of the injection fluid is recovered from thecollected reservoir fluid.
 52. A system for petroleum production from awell having a well section with a wellbore inner surface and an innerbore, the inner bore being communicable with fractures in a formationvia the wellbore inner surface, the system comprising: a conduitextending down the well, the conduit having a lower end in or near thewell section and being in fluid communication with the inner bore of thewell section; and a plurality of flow regulators at or near the wellboreinner surface, each being connected to at least one of the fractures andbeing selectively openable and closeable for allowing and blocking,respectively, fluid communication between the inner bore and the atleast one of the fractures.
 53. The system of claim 52 wherein the wellsection includes a casing with an outer surface and an inner surface,the inner surface being the wellbore inner surface, and the plurality offlow regulators are installed on the outer surface of the casing oroutside of the casing adjacent the outer surface thereof.
 54. The systemof claim 53 further comprising measurement and control systeminstrumentation which is installed outside of the casing adjacent theouter surface thereof.
 55. A method for petroleum production from a wellhaving a well section with a wellbore inner surface in communicationwith a plurality of fractures in a formation containing reservoir fluid,the method comprising: creating a plurality of zones in the wellsection, each zone for communicating with at least one of the pluralityof fractures and each zone being fluidly sealed from adjacent zones inthe well section, and two or more zones are fluidly connectable via aconduit extending through the plurality of zones; selectively supplyinginjection fluid from the conduit to at least one of the zones andinjecting the injection fluid into the formation via the at least one ofthe zones; selectively collecting reservoir fluid into the conduit fromthe formation via at least one of the zones, and the injection ofinjection fluid and the collection of reservoir fluid occurringasynchronously; transporting the collected reservoir fluid to surface.56. The method of claim 55, wherein each zone is associated with a flowregulator connected to the conduit, the flow regulator having an openposition which allows fluid flow therethrough and a closed positionwhich blocks fluid flow therethrough, for controlling one or both of:(i) flow of fluid into the zone; and (ii) flow of fluid out of the zone.